Conventionally, in an image forming apparatus such as a printer, a copying machine, a facsimile, a multifunction machine, for example, in a printer, an image forming unit, an LED head, a transfer roller, a fuser, a sheet cassette, and the like, are arranged. The image forming unit includes a photosensitive drum, a charging roller, a development roller, a development blade, a toner supply roller, a cleaning blade, and the like.
In the image forming unit, a surface of the photosensitive drum that is uniformly charged by the charging roller is exposed by the LED head and an electrostatic latent image is formed. Further, a toner as a developer that is contained in a toner container as a developer container that is formed inside a case of the image forming unit is supplied to the development roller by the toner supply roller, and the development blade causes the toner on the development roller to form a thin layer. Next, the toner on the development roller is attached to the electrostatic latent image on the surface of the photosensitive drum, and the electrostatic latent image is developed and a toner image is formed on the photosensitive drum.
A sheet fed out from the sheet cassette is carried to a transfer part that is formed between the photosensitive drum and the transfer roller, and, after the toner image is transferred by the transfer roller at the transfer part, is carried to the fuser. At the fuser, the toner image is fused and an image is formed. Toner remained on the photosensitive drum after the transfer is removed by the cleaning blade.
The photosensitive drum and the development roller are in contact with each other at a contact part, and the development roller and the toner supply roller are in contact with each other at a nip part. The toner is supplied by the toner supply roller to the development roller at the nip part and the toner on the development roller is supplied to the electrostatic latent image on the surface of the photosensitive drum at the contact part (for example, see Japanese Patent Laid-Open Publication No. H10-39628).
However, in the above-described conventional image forming unit, the toner in the toner container is likely to stagnate and image quality may deteriorate due to the stagnation of the toner.
A purpose of the present invention is to solve the above-described problem of the conventional image forming unit to provide an image forming unit and an image forming apparatus that allow occurrence of stagnation of a developer in a developer container to be prevented and image quality to be improved.